and adsorption plays an important role for improved efficiency in this composite, as
confirmed by Matos et al. (Matos et al. 2001). The improved degradation of phenol
might be credited to its strapping adsorption ability on the activated carbon, leading
to the transfer of pollutant to the photocatalytically active TiO 2 . Based on the
combined effect, fullerene functions as an important emerging candidate as a
carbon-based support material owing to the increased charge transfer property
between the fullerene and inorganic nanophotocatalysts such as TiO 2 via surface
group acidification. Additionally, the energy sensitization of fullerene would also
enhance its efficiency.
Carbon nanotubes, as compared with activated carbon, possess higher surface
area and therefore may further improve the capability of adsorption and
photodegradation. Moreover, carbon nanotube surface functionalities (like
hydroxyl, carbonyl, and carboxyl moieties) can be tailored to achieve improved
selective performance towards pollutant degradation (Carp et al. 2004; Sher Shah
et al. 2012). In this context, carbon nanotubes are outstanding candidates, allowing a
deeper insight into the interfacial interaction between semiconductor photocatalyst
and carbon materials. Because of their unique photonic and electronic features,
graphene is also composited with other inorganic materials to achieve the desired
performance. Several graphene composites, such as graphene/TiO 2 , graphene/AgX
(where X ¼ Cl, Br), graphene/Cu 2 O, and graphene/SnO 2 , have remarkable
photocatalytic activity (Seema et al. 2012, Sher Shah et al. 2012). Such composites
have a broad range of applications in wastewater treatment, such as photocatalytic
degradation of dyes and reduction of toxic metal ions. Fan et al. reported the
formation of three-dimensional (3D) composites made up of AgX (where X ¼ Cl,
Br) and graphene by using a deposition approach, in which AgX (where X ¼ Cl, Br)
nanoparticles are deposited on the surface of three-dimensional graphene via a facile
approach (Fan et al. 2015). Methyl orange and Cr(VI) ions were used to investigate
the photocatalytic degradation and reduction performance of the designed composite. The results revealed that the composite material exhibited better performance
than pristine AgX (where X ¼ Cl, Br) nanoparticles. The three-dimensional configuration of the composite allows its easy recyclability from the solution, which is very
significant for large-scale practical uses. The photocatalytic degradation activity of
the graphene/Cu 2 O crystal with different exposed facets was demonstrated via
methylene blue degradation under visible light, and best performance was achieved
using O-Cu 2 O/rGO composite. In contrast to these metal-based NP composites,
several metal-free composite nanomaterials even exhibit comparable
photodegradation performance. For example, Jiang et al. constructed a graphitic
carbon nitride (g-C 3 N 4 ) and graphene oxide composite through solvothermal
co-assembly approach (Tong et al. 2015). Graphene oxide functions as a support
for graphitic carbon nitride immobilization, which facilitates electron transfer,
whereas the graphitic carbon nitride functions as photocatalyst for the degradation
of methyl orange. Due to the synergetic effect of both components, the
photodegradation efficiency reaches up to 92% in 4 h under sunlight, which is
superior to sole graphitic carbon nitride (12%).
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B. Akram et al.
confirmed by Matos et al. (Matos et al. 2001). The improved degradation of phenol
might be credited to its strapping adsorption ability on the activated carbon, leading
to the transfer of pollutant to the photocatalytically active TiO 2 . Based on the
combined effect, fullerene functions as an important emerging candidate as a
carbon-based support material owing to the increased charge transfer property
between the fullerene and inorganic nanophotocatalysts such as TiO 2 via surface
group acidification. Additionally, the energy sensitization of fullerene would also
enhance its efficiency.
Carbon nanotubes, as compared with activated carbon, possess higher surface
area and therefore may further improve the capability of adsorption and
photodegradation. Moreover, carbon nanotube surface functionalities (like
hydroxyl, carbonyl, and carboxyl moieties) can be tailored to achieve improved
selective performance towards pollutant degradation (Carp et al. 2004; Sher Shah
et al. 2012). In this context, carbon nanotubes are outstanding candidates, allowing a
deeper insight into the interfacial interaction between semiconductor photocatalyst
and carbon materials. Because of their unique photonic and electronic features,
graphene is also composited with other inorganic materials to achieve the desired
performance. Several graphene composites, such as graphene/TiO 2 , graphene/AgX
(where X ¼ Cl, Br), graphene/Cu 2 O, and graphene/SnO 2 , have remarkable
photocatalytic activity (Seema et al. 2012, Sher Shah et al. 2012). Such composites
have a broad range of applications in wastewater treatment, such as photocatalytic
degradation of dyes and reduction of toxic metal ions. Fan et al. reported the
formation of three-dimensional (3D) composites made up of AgX (where X ¼ Cl,
Br) and graphene by using a deposition approach, in which AgX (where X ¼ Cl, Br)
nanoparticles are deposited on the surface of three-dimensional graphene via a facile
approach (Fan et al. 2015). Methyl orange and Cr(VI) ions were used to investigate
the photocatalytic degradation and reduction performance of the designed composite. The results revealed that the composite material exhibited better performance
than pristine AgX (where X ¼ Cl, Br) nanoparticles. The three-dimensional configuration of the composite allows its easy recyclability from the solution, which is very
significant for large-scale practical uses. The photocatalytic degradation activity of
the graphene/Cu 2 O crystal with different exposed facets was demonstrated via
methylene blue degradation under visible light, and best performance was achieved
using O-Cu 2 O/rGO composite. In contrast to these metal-based NP composites,
several metal-free composite nanomaterials even exhibit comparable
photodegradation performance. For example, Jiang et al. constructed a graphitic
carbon nitride (g-C 3 N 4 ) and graphene oxide composite through solvothermal
co-assembly approach (Tong et al. 2015). Graphene oxide functions as a support
for graphitic carbon nitride immobilization, which facilitates electron transfer,
whereas the graphitic carbon nitride functions as photocatalyst for the degradation
of methyl orange. Due to the synergetic effect of both components, the
photodegradation efficiency reaches up to 92% in 4 h under sunlight, which is
superior to sole graphitic carbon nitride (12%).
674
B. Akram et al.